Adaptive algorithm-based engine health prediction

ABSTRACT

A system and algorithm-based method of determining engine health and assuring available propulsion power based on historical data reflecting the individual engine&#39;s unique performance “fingerprint.”

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with Government support under contractN00019-09-D-0008 awarded by the Naval Air Systems Command. TheGovernment has certain rights in this invention.

FIELD OF THE INVENTION

The application generally relates to monitoring and predicting enginehealth and, more particularly, to a system and algorithm-based method ofdetermining engine health and assuring available propulsion power.

BACKGROUND OF THE INVENTION

Aircraft engine health is typically monitored using a Power AssuranceCheck (“PAC”). PACS generally measure and calculate engine horsepower asa function of measured gas temperature (“MGT”), corrected measured gastemperature (“MGTc”), or corrected gas generator speed (“NGc”) understeady operating conditions, before comparing that performance level toa baseline specification. The comparison to the baseline specificationprovides an indication of engine health level. PACs, however, haveseveral limitations.

As one example, a PAC requires several minutes of stable, steady-stateoperation—i.e., in the case of a rotorcraft, several minutes of hover—inorder to be performed accurately. To perform an automated PAC, arotorcraft might have to hover for up to five minutes in relativelystable, wind-free conditions. If such conditions are not maintained foran adequate time period, the PAC routine will abort. Alternatively, amanual PAC can be performed. While a manually performed PAC will notabort because of a shorter period of stable, steady-state operation,accuracy will suffer if the period of steady operation is significantlyshorter. Manually performed PACs also introduce human error in plottingperformance data points, charting a line or curve on a graph, andinterpreting the graph to predict available power and determine enginehealth. And manual performance of a PAC can be burdensome for a flightcrew, or require additional personnel. For instance, for an aircraftrequiring two pilots, one pilot must fly the aircraft while the otherrecords the data and interprets the results. Alternatively, the flightcrew could include a flight engineer to perform the PAC analysis, butthe additional crew member diminishes the aircraft's capacity.

Another limitation of PACs is that it generally assumes that if, forexample, an engine is providing 100%/o of baseline performance at oneload level, it will provide 100%/o performance at higher loads as well.But engine health often differs at different engine load levels. As aresult, for example, a PAC can indicate 100% engine health, only to havethe pilots find that only 94% of the predicted power level is actuallyavailable when they reach higher altitude, attempt to lift heavierloads, or enter worse operating environments. Thus, the flight crewmight find that the engine is marginal when its performance is mostcrucial.

Yet another limitation of PACs is that, for best accuracy, a PAC shouldbe performed at high engine loads, e.g., within about 100° F. of theengine's maximum MGT rating. But reaching such a high engine load canrequire high altitudes, heavier aircraft loads, and/or high outside airtemperatures. These can be difficult or impossible to acquire, dependingon conditions.

Consequently, a need exists for an engine health assessment system andmethod that: (1) does not require several minutes of stable,steady-state operation; (2) does not place a significant burden on theflight crew; (3) accurately predicts engine health and performancelevels at all operating loads and power levels, based on historical datareflecting the individual engine's unique performance “fingerprint”; and(4) does not require operation at high power levels and loads to obtainaccuracy. These and other advantages of the present invention willbecome apparent to one skilled in the art.

SUMMARY OF THE INVENTION

In one aspect, the invention includes a method for collecting enginedata for use in determining the health of an engine on an aircraft, themethod comprising: receiving engine operating information; determiningfrom the engine operating information a power parameter and a criticalparameter; recording as a data point the power parameter and thecritical parameter; and merging the data point with a stored data set,the stored data set including previously recorded power parameter andcritical parameter data points.

In another aspect, the invention includes a method of determining thehealth of an engine on an aircraft, the method comprising: selecting anengine performance curve to use in creating an engine health model;executing a curve-fitting process to obtain a fitted curve, the fittedcurve being based on the selected engine performance curve and a storeddata set; evaluating engine health by comparing the fitted curve to a100% specification-level performance curve for the engine; andoutputting engine health information.

In a third aspect, the invention includes a method of determining thehealth of an engine on an aircraft, the method comprising: receivingengine operating information; determining from the engine operatinginformation a power parameter and a critical parameter; recording as adata point the power parameter and the critical parameter; merging thedata point with a stored data set, the stored data set includingpreviously recorded power parameter and critical parameter data points;selecting an engine performance curve to use in creating an enginehealth model; obtaining a fitted curve by translating and rotating theselected engine performance curve to achieve a low error with respect tothe stored data set; evaluating engine health by comparing the fittedcurve to a 100% specification-level performance curve for the engine;and outputting engine health information.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features of certain embodiments of the present invention aredisclosed in the accompanying drawings, wherein similar referencecharacters denote similar elements throughout the several views, andwherein:

FIG. 1 shows a rotorcraft according to one embodiment;

FIG. 2 is a block diagram of an engine health system according to oneembodiment;

FIG. 3 is a flow chart of representing a data collection processaccording to one embodiment;

FIG. 4 is a flow chart of representing a process for determining enginehealth according to one embodiment;

FIG. 5 is a chart of collected data for use in a process for determiningengine health according to one embodiment;

FIG. 6 is the chart of collected data according to the embodiment ofFIG. 5, with a baseline engine performance curve introduced;

FIG. 7 is the chart of collected data according to the embodiment ofFIG. 6, with the baseline engine performance curve translated to achievethe lowest error with respect to the collected data points;

FIG. 8 is the chart of collected data according to the embodiment ofFIG. 7, with the baseline engine performance curve rotated to achievethe lowest error with respect to the collected data points; and

FIGS. 9 and 10 depict the chart of collected data according to theembodiment of FIG. 8, with the baseline engine performance curvereintroduced in its original position.

DETAILED DESCRIPTION

The embodiments of the present invention will now be described morefully, with reference to the accompanying drawings, in which preferredembodiments of the invention are shown. This invention may, however, beembodied in many different forms and should not be construed as limitedto the illustrated embodiments set forth herein. Rather, the illustratedembodiments are provided so that this disclosure will be thorough andcomplete and will convey the scope of the invention to those skilled inthe art.

In the interest of clarity and brevity, all features of an embodimentmay not be described. In the development of any actual embodiment,numerous implementation-specific decisions must be made to achieve thedeveloper's specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. While such a development effort might be complex andtime-consuming, it would, nevertheless, be a routine undertaking forthose of ordinary skill in the art having the benefit of thisdisclosure.

The invention is described, in part, with the help of functional and/orlogical block components, and with reference to symbolic representationsof operations, processing tasks, and functions that may be performed byvarious computing components or devices. Such operations, tasks, andfunctions are sometimes referred to as being computer-executed,computerized, software-implemented, or computer-implemented. Inpractice, one or more processor devices can carry out the describedoperations, tasks, and functions by manipulating electrical signalsrepresenting data bits at memory locations in the system memory, as wellas other processing of signals. The memory locations where data bits aremaintained are physical locations that have particular electrical,magnetic, optical, or organic properties corresponding to the data bits.It should be appreciated that the various block components shown in thefigures may be realized by any number of hardware, software, and/orfirmware components configured to perform the specified functions. Forexample, an embodiment of a system or a component may employ variousintegrated circuit components (e.g., memory elements, digital signalprocessing elements, logic elements, look-up tables, or the like), whichmay carry out a variety of functions under the control of one or moremicroprocessors or other control devices. Furthermore, the connectinglines shown in the various figures are intended to represent exemplaryfunctional relationships and/or physical couplings between the variouselements. However, one skilled in the art will appreciate that manyalternative or additional functional relationships or physicalconnections may be present in an embodiment.

FIG. 1 shows a rotorcraft 100 according to one example embodiment.Rotorcraft 100 features a rotor system 110, blades 120, a fuselage 130,a landing gear 140, and an empennage 150. Rotor system 110 may rotateblades 120. Rotor system 110 may include a control system forselectively controlling the pitch of each blade 120 in order toselectively control direction, thrust, and lift of rotorcraft 100.Fuselage 130 represents the body of rotorcraft 100 and may be coupled torotor system 110 such that rotor system 110 and blades 120 may movefuselage 130 through the air. Landing gear 140 supports rotorcraft 100when rotorcraft 100 is landing and/or when rotorcraft 100 is at rest onthe ground. Empennage 150 represents the tail section of the aircraftand features components of a rotor system 110 and blades 120′. Blades120′ may provide thrust in the same direction as the rotation of blades120 so as to counter the torque effect created by rotor system 110 andblades 120. It should also be appreciated that teachings regardingrotorcraft 100 may apply to aircraft and vehicles other than rotorcraft,such as airplanes and unmanned aircraft, to name a few examples.

Referring now also to FIG. 2, an exemplary engine health system 200includes an engine 201, which provides power to rotor system 110. Oneskilled in the art will appreciate that the engine health system 200may, alternatively, include multiple engines 201. The engine healthsystem 200 further includes one or more engine sensor devices 202, whichare configured to transmit engine operating information 220. Forexample, engine sensor devices 202 may measure, calculate, estimate,and/or transmit information such as MGT, MGTc, NGc, torque output,horsepower output, etc. The engine sensor devices 202 provide the engineoperating information 220 via an aircraft data bus 203. Aircraft databus 203 may be a conductive-wire serial data bus, such as a data buscompliant with MIL-STD-1553, or a fiber optic data bus, such as a databus compliant with MIL-STD-1773. An engine health monitoring device 204collects the engine operating information 220 via the aircraft data bus203 and processes the engine operating information 220 as describedbelow with reference to FIGS. 3-10.

After processing the engine operating information 220 collected from theaircraft data bus 203, the engine health monitoring device 204 providesengine health information 230 to one or more output devices. In theembodiment of FIG. 2, the output devices include: data storage device205, flight crew interface device 206, and transceiver device 207. Whileengine health monitoring device 204, data storage device 205, flightcrew interface device 206, and transceiver device 207 are depicted asbeing separate devices, one of ordinary skill in the art will appreciatethat two or more of these devices may be combined into a singlecomponent. For instance, in an alternative embodiment, all of thesedevices 204, 205, 206, 207 may be integrated into a single component.Additionally, FIG. 2 depicts a data storage device 205, a flight crewinterface device 206, and a transceiver device 207 each connecteddirectly to the engine health monitoring device 204. However, a varietyof physical connections among these devices is possible. For example, inan alternative embodiment, each of these devices may be interconnectedvia the aircraft data bus 203.

Data storage device 205 is configured to store the engine healthinformation 230 for retrieval. As one example, data storage device 205may include a data port that allows the engine health information 230 tobe downloaded and analyzed at regular intervals. Data storage device 205may be queried, either by on-board systems that provide periodic oron-demand queries, or by an off-aircraft maintenance and diagnostic tool209. More specifically, such queries may be generated by—or communicatedthrough—aircraft data bus 203, the engine health monitoring device 204,flight crew interface device 206, off-aircraft maintenance anddiagnostic tool 209, and/or other components and systems. Whenresponding to a query, data storage device 205 communicates enginehealth information 230 to one or more of the aircraft data bus 203,engine health monitoring device 204, flight crew interface device 206,transceiver device 207, base station 208, off-aircraft maintenance anddiagnostic tool 209, and/or other components and systems. Data storagedevice 205 can also serve as a repository for the stored data set 330(see FIGS. 5-10).

Flight crew interface device 206 is configured to provide the enginehealth information 230 to the flight crew. As one example, the flightcrew interface device 206 may include a gauge or display screen thatindicates engine health information 230. Such gauges or display screensmay continuously indicate the engine health information 230, or suchinformation 230 may be available on-demand. For example, a buttonpressed in the cockpit may prompt engine health information 230 tobecome displayed on a screen. As another example, the flight crewinterface device 206 may include warning indicators, lights, tactilealerts, or audible alarms that alert the flight crew in the event thatthe engine health information 230 falls outside of a predeterminedrange.

Transceiver device 207 is configured to transmit engine healthinformation 230 off-aircraft. For example, transceiver device 207 maytransmit engine health information 230 to a base station 208 while theaircraft is in operation. Base station 208 may be a maintenancedatabase, grounds crew, mobile command center, chase vehicle oraircraft, etc. One skilled in the art will appreciate that transceiverdevice 207 need not be a dedicated transceiver operable to transmit andreceive only engine health 230 and related information. Rather,transceiver device 207 may be a multipurpose transceiver configured totransmit and receive other information in addition to engine healthinformation 230, including for example, voice data, GPS data, HUMS data,control commands in the case of an unmanned vehicle, etc.

Referring still to the embodiment of FIG. 2, other aircraft systems 210are in communication with aircraft data bus 203. More specifically,other sensors and processors make available via the aircraft data bus203 additional information relating to the aircraft and/or the operatingenvironment 240, for instance: (1) altitude; (2) outside airtemperature; (3) whether there is weight on the landing gear 140; (4)whether the aircraft is flying in helicopter mode, airplane mode, orsomewhere in between (in the case of a tiltrotor or tiltwing aircraft);(5) engine inlet configuration or restriction information; and/or (6)exhaust configuration or restriction information. The engine healthmonitoring device 204 may optionally process this additional information240, along with the engine operating information 220, in order todetermine the engine health information 230.

FIGS. 3 and 4 depict flowcharts for a data collection process 300 and aprocess for determining engine health 400, respectively. These processes300, 400 may be performed by software, hardware, firmware, or anycombination thereof. In one example, engine health monitoring device 204(see FIG. 2) performs the data collection process 300 and process fordetermining engine health 400. In another example, portions of theseprocesses 300, 400 relating to the storage of the stored data set 330(see FIGS. 5-10) are performed by data storage device 205. Accordingly,one of ordinary skill will appreciate that various elements and devicescan perform all or portions of the processes 300, 400 without departingfrom the scope of the invented method.

FIG. 3 depicts an exemplary data collection process 300. The datacollection process 300 includes the steps of receiving 301 engineoperating information 220 and receiving 302 additional informationrelating to the aircraft and/or the operating environment 240. Theengine operating information 220 and additional information 240 mayoptionally be received from aircraft data bus 203 (see FIG. 2).

The data collection process 300 further includes determining 303 whetherthe engine operating information 220 represents a stable data point 320(see FIGS. 5-10). That is, one or more mathematical data noise-reductionprocesses, which are generally known in the art, are applied to theengine operating information 220. As one example, one or more lagfilters may be applied to the engine operating information 220. If thenoise-reduction process reveals that the engine operating information220 does not represent a stable data point 320, then the engineoperating information 220 is discarded, and the data collection process300 restarts 304.

The data collection process 300 further includes determining 305 whetherthe engine operating information 220 represents a valid data point 320(see FIGS. 5-10). Various validity criteria may be selected and verifiedin order to determine whether the engine operating information 220represents a valid data point 320. Such validity criteria may requirereference to engine operating information 220 and/or additionalinformation relating to the aircraft and/or the operating environment240. For instance, one validity criteria may be that there is no weighton the landing gear 140 (see FIG. 1). Another exemplary validitycriteria may be that MGT is greater than 1000° F. If all of the validitycriteria are not met, then the engine operating information 220 isdiscarded, and the data collection process 300 restarts 304.

The data collection process 300 depicted in FIG. 3 includes the furtherstep of determining and recording 307 a power parameter (e.g., torquevalue, power value, torque margin, or power margin) and a criticalparameter (e.g., MGT, MGTc, or NGc value), from the engine operatinginformation 220, as a data point 320 (see FIGS. 5-10). Morespecifically, in the embodiment of FIG. 3, the power margin, or “delta”between the 100% specification-level performance power and the actualmeasured power, for the given MGT, is determined. Once determined, thepower margin and MGT data is then recorded as a data point 320 forfurther processing. One of ordinary skill in the art will appreciatethat, alternatively, MGTc or NGc data might be recorded as a criticalparameter in addition to, or in place of, MGT. Preferentially, MGT/MGTcdata will be recorded if the engine ordinarily reaches its MGT limitbefore it reaches its NGc limit. And, conversely, NGc data will berecorded if the engine ordinarily reaches its NGc limit before itreaches its MGT limit.

In the embodiment of FIG. 3, the determining and recording step 307 alsoincludes “correcting” the power parameter and the critical parameterbased on additional information relating to the aircraft and/or theoperating environment 240. For instance, if the outside air temperatureis high, then a correction factor may be applied to the power margindata and MGT data, before the data point 320 is recorded. In thisscenario, the data point 320 is corrected or normalized to eliminatevariations in performance attributable to current installation losses,operating configurations, and environmental conditions. The resulting“corrected” data point 320, therefore, represents the engine's power ifit were performing on a test stand under ideal conditions or standardconditions, at the given MGT, rather than installed on an aircraft andsubjected to varying operating configurations and environmentalconditions. Such a correction may be necessary, for instance, if thepower parameter is MGT because the stored data set 330 will otherwisecontain scattered data points 320, which may not be reduced to a fittedcurve 440 (see FIGS. 5-10) due to the influence of other variables. Itis, therefore, preferable that the stored data set 330 include correcteddata points 320 (i.e., corrected power margin and MGTc values) ratherthan observed values (i.e., observed power margin and MGT values).

In an alternative embodiment, the raw values (i.e., the actual measuredpower—rather than a power margin—and the measured MGT) is recorded forfurther processing. However, it may be advantageous to record as a datapoint 320 only the power margin and MGTc data in order to optimize datahandling and processing.

The data collection process 300, as depicted in FIG. 3, also includesmerging 308 the recorded data point 320 with a stored data set 330. Thestored data 330 set includes historical data points 320, based onprevious power margin data and MGTc data. Merging 308 the newly recordeddata point 320 with the stored data set 330 may include grouping the newdata point 320 with statistically similar historical data points in thestored data set 330, and merging those statistically similar data pointsinto a single, representative data point. This merging step 308 mayfurther include purging one or more older data points from the storeddata set 330. In this way, the stored data set 330 may change over timeas new data is merged and old data is purged. The stored data set 330,therefore, is constantly updated to reflect the recent historical powermargin (i.e., the “performance fingerprint”) for the individual engine.

Referring still to FIG. 3, the process 300 includes the additional stepof determining 309 whether to invoke the process for determining enginehealth 400. The process for determining engine health 400, which is usedto determine engine health information 230, can be set to occur, forexample, based on any combination of the following: (1) periodicallybased on time (e.g., every minute); (2) periodically based on flighthours (e.g., every fifteen minutes of flight time); (3) on demand (e.g.,when the flight crew queries engine health information 230); (4) whenengine health information 230 is transmitted off of the aircraft (e.g.,when retrieved by a maintenance or diagnostic tool 209, or whentransmitted to a base station 208 by a transceiver device 207); and/or(5) when recent power margin and MGTc data points 320 depart fromhistorical data in the stored data set 330, potentially indicating asudden or rapid degradation of engine health (e.g., when an enginesuffers damage ingests foreign material). If, under one or more of thepotential criteria, updating the engine health information 230 is due,then the process 400 (described in detail below, with reference to FIGS.4-10) occurs. If, however, updating the engine health information 230 isnot yet due to occur, then the data collection process 300 restarts 304.

FIG. 4 depicts an exemplary process for determining engine health 400.The process for determining engine health 400 includes selecting 401 anengine performance curve 430 to use in creating an engine health model.For instance, the selected performance curve 430 could be the engine's100% specification-level performance curve 450 (see FIGS. 9-10).Alternatively, the selected performance curve 430 could be the engine'sfully-deteriorated performance curve. As yet another example, theprocess 400 could select both the 100% specification-level performancecurve 450 and the fully-deteriorated performance curve. In such anexample, the analysis would proceed using both performance curves, andthe curve that best fits the data would become the selected performancecurve 430 used in creating an engine health model.

The process for determining engine health 400 further includes acurve-fitting process 402. The curve-fitting process 402 includestranslating and rotating the selected performance curve 430 to best fitthe stored data set 330. The process for determining engine healthfurther includes the step of evaluating engine health 403. In this step,the fitted curve 440 resulting from the curve-fitting process 402 iscompared to the 100% specification-level performance curve 450, toobtain an estimate for overall engine health. In addition, or as analternative, the fitted curve 440 can also be evaluated at anextrapolation point 460 in order to determine an expected power margin,or performance level, at a given load (i.e., at a given MGT or MGTc).The engine health information 230 discussed above with reference to FIG.2 may comprise an overall engine health estimate and/or an expectedpower margin at a given load. The curve-fitting process 402 andevaluation step 403 are described in greater detail below, withreference to FIGS. 5-10.

The process for determining engine health 400 further includesoutputting 404 the resulting engine health information 230. Exemplaryoutput devices (i.e., 205, 206, 207) and associated methods arediscussed above, with reference to FIG. 2.

Referring to FIG. 5, the curve-fitting process 402 of the depictedembodiment includes charting the stored data set 330, which comprises aconstantly updating set of data points 320 representing historical powermargin (y-axis) as a function of MGTc data (x-axis). As discussed above,the illustrated embodiment includes the steps of determining whethereach data point is stable 303 and valid 305 as part of the datacollection process 300 (see FIG. 3). However, one of ordinary skill willreadily appreciate that these data-filtering steps can, alternatively,be taken as part of the curve-fitting process 402. That is, all datapoints 320 might be recorded as part of the stored data set 330. Butwhen the curve-fitting process 402 begins with charting the stored dataset 330, each data point 320 that is not both stable and valid may beignored.

FIGS. 6-8 illustrate additional steps in the curve-fitting process 402.Referring to FIG. 6, the curve-fitting process 402 includes introducingthe selected engine performance curve 430, which was selected as part ofstep 401 (see FIG. 4). As best shown in FIG. 7, the selected engineperformance curve 430 is then translated (i.e., shifted withoutrotation) to achieve the lowest error with respect to the stored dataset 330. This results in a translated curve 435. As illustrated in FIG.8, the translated curve 435 is then rotated to achieve the lowest errorwith respect to the stored data set 330. This results in a fitted curve440. One of ordinary skill in the art will appreciate that,alternatively, the rotation step (FIG. 8) could occur before translation(FIG. 7).

The translation and rotation of the selected engine performance curve430 is preferably achieved based on an “optical fit.” That is, the curveis translated and rotated so as to minimize the apparent error, oraverage distance, between the fitted curve 440 and the collection ofdata points 320. In alternative embodiments, a polynomial least squaremethod can be used to as a fitting routine to create the fitted curve440. However, extrapolations from a fitted curve 440 that results from apolynomial least squares fitting method may be less reliable.

FIGS. 9 and 10 illustrate the step of evaluating engine health 403. Asbest shown in FIG. 9, the 100% specification-level performance curve 450is introduced. The margins 455 between the fitted curve 440 and the 100%specification-level performance curve 450, are evaluated at variouspoints to determine an overall estimate of engine health. As one skilledin the art will appreciate, this can be accomplished using well-knownstatistical methods.

Additionally, or as an alternative, FIG. 10 illustrates that the fittedcurve 440 can be compared to the 100% specification-level performancecurve 450, at a specific point 460, to determine the expected powermargin 465 at a given load (i.e., at a given MGTc or MGT).

Whether the engine health information 230 takes the form of an overallestimate of engine health (FIG. 9), or an expected power margin at agiven load (FIG. 10), the step of evaluating engine health 403 mayinclude “correcting” the margin data 455, 465 based on the additionalinformation relating to the aircraft and/or the operating environment240. For instance, if the outside air temperature is high, then acorrection factor may be applied to the power margin data 455, 465before it is used to determine the engine health information 230 thatwill be output. That is, the margin data 455, 465 is corrected ornormalized to eliminate variations in performance attributable tocurrent installation losses, operating configurations, and environmentalconditions. The resulting “corrected” engine health information 230,therefore, may represent the engine's power under real-world, installedconditions, rather than theoretical performance levels.

Modifications, additions, or omissions may be made to the systems andapparatuses described herein without departing from the scope of theinvention. The components of the systems and apparatuses may beintegrated or separated. Moreover, the operations of the systems andapparatuses may be performed by more, fewer, or other components. Themethods may include more, fewer, or other steps. Additionally, steps maybe performed in any suitable order.

Although several embodiments have been illustrated and described indetail, it will be recognized that substitutions and alterations arepossible without departing from the spirit and scope of the presentinvention, as defined by the appended claims.

To aid the Patent Office, and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims to invoke 35U.S.C. § 112(f) as it exists on the date of filing hereof unless thewords “means for” or “step for” are explicitly used in the particularclaim.

1-20. (canceled)
 21. A method of reflecting recent corrected engineperformance in a data storage device on an aircraft, the methodcomprising, by a computer comprising a processor and memory: receiving,from an engine sensor coupled to the computer, engine operatinginformation for an engine on the aircraft; determining, from the engineoperating information, a power parameter and a critical parameter,correcting the power parameter and the critical parameter based onadditional information available in an aircraft data bus on theaircraft; recording, as a data point in a stored data set in the datastorage device, the corrected power parameter and the corrected criticalparameter; grouping the data point with statistically similar historicaldata points in the stored data set; merging the data point and thestatistically similar historical data points into a singlerepresentative data point in the stored data set, the stored data setincluding previously recorded power parameter and critical parameterdata points; and purging one or more older data points in the storeddata set.
 22. The method according to claim 21, wherein the receivingthe engine operating information includes receiving the engine operatinginformation from the aircraft data bus.
 23. The method according toclaim 21, wherein the critical parameter is an MGT value.
 24. The methodaccording to claim 21, wherein the power parameter is a power margin.25. The method according to claim 21, wherein the data point representsthe engine's power if it were performing on a test stand under standardconditions.
 26. The method according to claim 21, further comprising:determining whether the power parameter and the critical parameterrepresent a stable data point; and discarding the engine operatinginformation in the event that the power parameter and the criticalparameter do not represent a stable data point.
 27. The method accordingto claim 21, further comprising: determining whether the power parameterand the critical parameter represent a valid data point; and discardingthe engine operating information in the event that the power parameterand the critical parameter do not represent a valid data point.
 28. Themethod according to claim 27, wherein the determining whether the powerparameter and the critical parameter represent a valid data pointcomprises determining whether there is weight on landing gear.
 29. Themethod according to claim 21, wherein the correcting comprises applyinga correction factor based on an outside air temperature.
 30. A computersystem comprising a processor and memory, wherein the processor and thememory in combination implement a method of reflecting recent correctedengine performance in a data storage device on an aircraft, the methodcomprising: receiving, from an engine sensor coupled to the computersystem, engine operating information for an engine on the aircraft;determining, from the engine operating information, a power parameterand a critical parameter; correcting the power parameter and thecritical parameter based on additional information available in anaircraft data bus on the aircraft; recording, as a data point in astored data set in the data storage device, the corrected powerparameter and the corrected critical parameter; grouping the data pointwith statistically similar historical data points in the stored dataset; merging the data point and the statistically similar historicaldata points into a single representative data point in the stored dataset, the stored data set including previously recorded power parameterand critical parameter data points; and purging one or more older datapoints in the stored data set.
 31. The computer system according toclaim 30, wherein the receiving the engine operating informationincludes receiving the engine operating information from the aircraftdata bus.
 32. The computer system according to claim 30, wherein thecritical parameter is an MGT value.
 33. The computer system according toclaim 30, wherein the power parameter is a power margin.
 34. Thecomputer system according to claim 30, wherein the data point representsthe engine's power if it were performing on a test stand under standardconditions.
 35. The computer system according to claim 30, the methodfurther comprising: determining whether the power parameter and thecritical parameter represent a stable data point; and discarding theengine operating information in the event that the power parameter andthe critical parameter do not represent a stable data point.
 36. Thecomputer system according to claim 30, the method further comprising:determining whether the power parameter and the critical parameterrepresent a valid data point; and discarding the engine operatinginformation in the event that the power parameter and the criticalparameter do not represent a valid data point.
 37. The method accordingto claim 36, wherein the determining whether the power parameter and thecritical parameter represent a valid data point comprises determiningwhether there is weight on landing gear.
 38. The computer systemaccording to claim 30, wherein the correcting comprises applying acorrection factor based on an outside air temperature.
 39. Acomputer-program product comprising a non-transitory computer-usablemedium having computer-readable program code embodied therein, thecomputer-readable program code adapted to be executed to implement amethod of reflecting recent corrected engine performance in a datastorage device on an aircraft, the method comprising: receiving, from anengine sensor coupled to a computer, engine operating information for anengine on the aircraft; determining, from the engine operatinginformation, a power parameter and a critical parameter; correcting thepower parameter and the critical parameter based on additionalinformation available in an aircraft data bus on the aircraft;recording, as a data point in a stored data set in the data storagedevice, the corrected power parameter and the corrected criticalparameter; grouping the data point with statistically similar historicaldata points in the stored data set; merging the data point and thestatistically similar historical data points into a singlerepresentative data point in the stored data set, the stored data setincluding previously recorded power parameter and critical parameterdata points; and purging one or more older data points in the storeddata set.
 40. The computer-program product according to claim 39,wherein the receiving the engine operating information includesreceiving the engine operating information from the aircraft data bus.